- #1
mr1709
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1. A spring is suspended from a ceiling and a 256g mass is attached to it and pulled down to stretch the spring by 18.2cm The mass is released and travels through the equilibirum position with a speed of 0.746m/s. Calculate the force of the spring constant
Solution
Et= Et'
Ee = Ek + Eg
0.5kx^2 = 0.5mv^2 + mgy
k = (mv^2 + 2mgy)/x^2
So i was doing this question online and saw the solution and have no issue with solving it after seeing how it was solved. My only issue is regarding the theory of this question and was hoping maybe somoene could explain to me.
So the solution involves equating Ee = EG + Ek, but i don't really understand why eg+ek is equal to Ee. I get that when the spring is stretched down it only has elastic potential energy, but then why when its released does the elastic energy equal the sum of gravitational energy and kinetic energy. And why is the y in mgy equal to the same value as x in the spring formula 0.5kx^2
My only reasoning which i still don't fully understand is that when the spring is in its equlibirium position as its released...Ee= 0 and all the energy is now converted to another form. I initially thought that all the energy became kinetic energy, but why is some gravitational as well?
Solution
Et= Et'
Ee = Ek + Eg
0.5kx^2 = 0.5mv^2 + mgy
k = (mv^2 + 2mgy)/x^2
So i was doing this question online and saw the solution and have no issue with solving it after seeing how it was solved. My only issue is regarding the theory of this question and was hoping maybe somoene could explain to me.
So the solution involves equating Ee = EG + Ek, but i don't really understand why eg+ek is equal to Ee. I get that when the spring is stretched down it only has elastic potential energy, but then why when its released does the elastic energy equal the sum of gravitational energy and kinetic energy. And why is the y in mgy equal to the same value as x in the spring formula 0.5kx^2
My only reasoning which i still don't fully understand is that when the spring is in its equlibirium position as its released...Ee= 0 and all the energy is now converted to another form. I initially thought that all the energy became kinetic energy, but why is some gravitational as well?
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